Game Engine: Level of detail support and tools

Levels of detail can be added and modified in the object panel. The object
panel also contains new tools for generating levels of detail, setting up
levels of detail based on object names (useful for importing), and
clearing an object's level of detail settings. This is meant as a game
engine feature, though the level of details settings can be previewed in
the viewport.

Reviewed By: moguri, nexyon, brecht

Differential Revision: http://developer.blender.org/D109

release/scripts/startup/bl_operators/object.py

@@ -775,3 +775,154 @@ class DupliOffsetFromCursor(Operator):
         ob.users_group[group].dupli_offset = scene.cursor_location
 
         return {'FINISHED'}
+
+
+class LodByName(Operator):
+    """Add levels of detail to this object based on object names"""
+    bl_idname = "object.lod_by_name"
+    bl_label = "Setup Levels of Detail By Name"
+    bl_options = {'REGISTER', 'UNDO'}
+
+    @classmethod
+    def poll(cls, context):
+        return (context.active_object is not None)
+
+    def execute(self, context):
+        scene = context.scene
+        ob = context.active_object
+        
+        prefix = ""
+        suffix = ""
+        name = ""
+        if ob.name.lower().startswith("lod0"):
+            prefix = ob.name[:4]
+            name = ob.name[4:]
+        elif ob.name.lower().endswith("lod0"):
+            name = ob.name[:-4]
+            suffix = ob.name[-4:]
+        else:
+            return {'CANCELLED'}
+
+        level = 0
+        while True:
+            level += 1
+
+            if prefix:
+                prefix = prefix[:3] + str(level)
+            if suffix:
+                suffix = suffix[:3] + str(level)
+
+            lod = None
+            try:
+                lod = bpy.data.objects[prefix + name + suffix]
+            except KeyError:
+                break
+
+            try:
+                ob.lod_levels[level]
+            except IndexError:
+                bpy.ops.object.lod_add()
+
+            ob.lod_levels[level].object = lod
+
+        return {'FINISHED'}
+
+
+class LodClearAll(Operator):
+    """Remove all levels of detail from this object"""
+    bl_idname = "object.lod_clear_all"
+    bl_label = "Clear All Levels of Detail"
+    bl_options = {'REGISTER', 'UNDO'}
+
+    @classmethod
+    def poll(cls, context):
+        return (context.active_object is not None)
+
+    def execute(self, context):
+        scene = context.scene
+        ob = context.active_object
+
+        if ob.lod_levels:
+            while 'CANCELLED' not in bpy.ops.object.lod_remove():
+                pass
+
+        return {'FINISHED'}
+
+
+class LodGenerate(Operator):
+    """Generates levels of detail using the decimate modifier"""
+    bl_idname = "object.lod_generate"
+    bl_label = "Generate Levels of Detail"
+    bl_options = {'REGISTER', 'UNDO'}
+
+    count = bpy.props.IntProperty(name="Count", default=3)
+    target = bpy.props.FloatProperty(name="Target Size", default=0.1,
+                                        min=0.0, max=1.0)
+    package = bpy.props.BoolProperty(name="Package into Group", default=False)
+    
+    @classmethod
+    def poll(cls, context):
+        return (context.active_object is not None)
+
+    def execute(self, context):
+        scene = bpy.context.scene
+        ob = scene.objects.active
+
+        lod_name = ob.name
+        lod_suffix = "lod"
+        lod_prefix = ""
+        if lod_name.lower().endswith("lod0"):
+            lod_suffix = lod_name[-3:-1]
+            lod_name = lod_name[:-3]
+        elif lod_name.lower().startswith("lod0"):
+            lod_suffix = ""
+            lod_prefix = lod_name[:3]
+            lod_name = lod_name[4:]
+
+        group_name = lod_name.strip(' ._')
+        if self.package:
+            try:
+                bpy.ops.object.group_link(group=group_name)
+            except TypeError:
+                bpy.ops.group.create(name=group_name)
+
+        step = (1.0 - self.target) / (self.count - 1)
+        for i in range(1, self.count):
+            scene.objects.active = ob
+            bpy.ops.object.duplicate()
+            lod = bpy.context.selected_objects[0]
+
+            scene.objects.active = ob
+            bpy.ops.object.lod_add()
+            scene.objects.active = lod
+
+            if lod_prefix:
+                lod.name = lod_prefix + str(i) + lod_name
+            else:
+                lod.name = lod_name + lod_suffix  + str(i)
+
+            lod.location.y = ob.location.y + 3.0 * i
+
+            if i == 1:
+                modifier = lod.modifiers.new("lod_decimate", "DECIMATE")
+            else:
+                modifier = lod.modifiers[-1]
+                
+            modifier.ratio = 1.0 - step*(i)
+
+            ob.lod_levels[i].object = lod
+
+            if self.package:
+                bpy.ops.object.group_link(group=group_name)
+                lod.parent = ob
+
+        if self.package:
+            for level in ob.lod_levels[1:]:
+                level.object.hide = level.object.hide_render = True
+
+        lod.select = False
+        ob.select = True
+        scene.objects.active = ob
+
+        return {'FINISHED'}
+